More than a third (28) of the deaths reported by the IRR are people suspected or known to have taken their own lives after their asylum claims had been turned down. Seven are said to have died after being denied health care for "preventable medical problems", seven are said to have died in prison custody, and 15 are said to have died during desperate and "highly risky" attempts to enter the country.

The report, which chronicles the often invisible lives and deaths of asylum seekers as they struggle to gain status in Britain, comes less than a week after the death of Jimmy Mubenga, 46, who died while being deported to Angola, and includes his death.

Witnesses have told the Guardian that the father of five collapsed after being restrained by security guards and complaining of breathing problems.

Not all the deaths in the report, which the IRR said was likely to be an underestimate, could be independently verified, although some have been extensively reported.

The IRR said the 77 deaths, most of which happened in the UK, were a consequence of "direct racism or indirect racism stemming from" asylum and immigration policies.

Among the seven that the IRR claims died in prison custody are Abdullah Hagar Idris, 18, a Sudanese asylum seeker found hanged in his cell on Christmas Day 2007, after being told wrongly he was to be deported, and Aleksey Baranovsky, 33, a Ukrainian national on suicide watch who bled to death in a cell at Rye Hill, Warwickshire in June 2006.

In June, an inquest jury said failings by the Prison Service and Essex social services contributed to Idris's death and criticised the way the prison gave him news of his deportation. Last year, a coroner condemned the "appalling and unacceptable conditions" and treatment at the GSL-run prison where Baranovsky died.

Baranovsky, who feared he would be killed by the Russian mafia if sent home, repeatedly harmed himself in protest against his pending deportation after serving a seven-year sentence for burglary.

The report, Driven to Desperate Measures, published today says the number of deaths of asylum seekers in the community has increased and now averages one a month.

However, it also says that, due to the difficulty of obtaining figures, this is likely to be an underestimate.

Over the four-year period, it recorded one death as having taken place during deportation – that of Mubenga, who died last week as he was being deported to Luanda, escorted by three guards from G4S, a private security company.

Those said by IRR to have died as a result of being denied access to medical treatment include Ama Sumani, a Ghanaian woman who died in March 2008, following deportation from Britain while undergoing treatment for terminal cancer.

Her deportation was described as "atrocious barbarism" by the Lancet medical journal.

It also lists Mohammed Ahmedi, 18, an asylum seeker with a heart condition who died as doctors tried to establish whether he was entitled to treatment on the NHS. Gloucester Royal hospital, where Ahmedi died in February 2008 after being treated there, has said treatment was not withheld.

The 77 deaths include seven who died on the streets in attacks "at the hands of racists", four after deportation back to a country where they feared for their safety, two as a result of becoming "destitute and unable to access services", and four as a result of often dangerous work in the "black economy", the report said.

It said that "hundreds if not thousands" of people had perished making desperate journeys to the UK, as stowaways on planes, lorries and ships.

Harmit Athwal, a researcher at IRR and the report's author, said: "Racism percolates right through the immigration-asylum system – from forcing people to risk life and limb to enter, forcing them to live destitute on the street, prey to violent racist attack. That 28 people died at their own hand, preferring this to being returned, when their asylum application failed, to the country they fled, is a terrible indictment of British justice.

"Asylum seekers are demonised by the mass media as illegals and scroungers and to appease popular racism, governments across Europe, in addition to making access to refugee status much more difficult, have decided to accelerate the deportation of the many who have 'failed'.

"Such forced deportations of those terrified of being returned to the countries they have fled – often areas in which we are involved and at war – will inevitably lead to more deaths."

The fate of Osman Rasul

Last July, Osman Rasul perched himself on railings at the top of a seven-storey tower block in Nottingham, and, ignoring efforts of police officers to talk him down, placed his hand on his heart, looked up to the sky, and jumped to his death.

Rasul was an Iraqi Kurd aged 27, who had been classified by the local refugee centre as a "destitute asylum seeker", having lost the legal aid to pursue his application to remain in the UK after the charity helping him, Refugee and Migrant Justice, went into administration. His relationship with the mother of his two children had broken down.

He arrived in 2001 claiming he was in danger from the political factions running northern Iraq. After being refused permission to stay, he was preparing a fresh claim. He was not allowed to work, and got food parcels and £10 a month from the Nottingham Refugee Forum.

On a trip to Croydon to confront Home Office immigration officers, he was turned away and told to find a solicitor. It was the last straw, said his friends, who described him as a "warm, kind, respectful man". One, Corin Faife, spoke of an "unbearable strain" Rasul had felt.

Writing in Ceasefire magazine, Faife said: "Living with Osman I saw first hand the spirit-crushing inhumanity of the British asylum system, and how unremittingly bleak life can be for those who are left in limbo. Prohibited from working, with no access to housing or financial support after his first claim was rejected, and still awaiting further documents to make a fresh claim, he was left destitute, forced to rely on the charity of others to his continual chagrin."

His friend's mental health, which had shown signs of fragility, started to decline before his trip to London, at which point, "the light at the end of the tunnel, which had kept him going for so long, flickered out".

A website was set up to raise money to repatriate Rasul's body and to promote awareness of the "struggles which he and so many others like him face". His body was sent to his family in Iraq and a funeral held on 6 August.